Dataset Information

Genetic variations of body weight and GCRV resistance in a random mating population of grass carp.

ABSTRACT: The grass carp (Ctenopharyngodon idellus) is an important species in freshwater aquaculture both in China and on a global scale. Variety degeneration and frequent diseases have limited the further development of grass carp aquaculture. Thus, new and improved varieties are required. Here, we identified and assessed the body weight and disease resistance in a random mating population of 19 â?? × 22 â?? grass carp, which were derived from different water systems. In both the growth experimental group of 10,245 fish and grass carp reovirus (GCRV)-infected group with 10,000 fish, 78 full-sib families were statistically analyzed for body weight and GCRV resistance. The findings showed that body weight traits had low heritability (0.11 ± 0.04, 0.10 ± 0.03 and 0.12 ± 0.05), GCRV resistance traits had high heritability (0.63 ± 0.11); body weight was higher in 3 families, whereas GCRV resistance was significantly greater in 11 families. Our results confirmed that the natural germplasm resources of wild grass carp were genetically diverse. Breeding of GCRV resistant varieties of grass carp have better genetic basis. This study provides the basis for constructing basal populations for grass carp selective breeding, quantitative trait loci (QTL) and genome-wide association studies (GWAS) analysis.

SUBMITTER: Huang R

PROVIDER: S-EPMC4742116 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Genetic variations of body weight and GCRV resistance in a random mating population of grass carp.

Huang Rong R Sun Jiaxian J Luo Qing Q He Libo L Liao Lanjie L Li Yongming Y Guo Fuhua F Zhu Zuoyan Z Wang Yaping Y

Oncotarget 20151101 34

The grass carp (Ctenopharyngodon idellus) is an important species in freshwater aquaculture both in China and on a global scale. Variety degeneration and frequent diseases have limited the further development of grass carp aquaculture. Thus, new and improved varieties are required. Here, we identified and assessed the body weight and disease resistance in a random mating population of 19 â × 22 â grass carp, which were derived from different water systems. In both the growth experimental gro ...[more]

PMID: 26439690

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Project description:The grass carp reovirus (GCRV) causes severe hemorrhagic disease with high mortality and leads to serious economic losses in the grass carp (Ctenopharyngodon idella) industry in China. Oral vaccine has been proven to be an effective method to provide protection against fish viruses. In this study, a recombinant baculovirus BmNPV-VP35-VP4 was generated to express VP35 and VP4 proteins from GCRV type ? via Bac-to-Bac baculovirus expression system. The expression of recombinant VP35-VP4 protein (rVP35-VP4) in Bombyx mori embryo cells (BmE) and silkworm pupae was confirmed by Western blotting and immunofluorescence assay (IFA) after infection with BmNPV-VP35-VP4. To vaccinate the grass carp by oral route, the silkworm pupae expressing the rVP35-VP4 proteins were converted into a powder after freeze-drying, added to artificial feed at 5% and fed to grass carp (18 ± 1.5 g) for six weeks, and the immune response and protective efficacy in grass carp after oral vaccination trial was thoroughly investigated. This included blood cell counting and classification, serum antibody titer detection, immune-related gene expression and the relative percent survival rate in immunized grass carp. The results of blood cell counts show that the number of white blood cells in the peripheral blood of immunized grass carp increased significantly from 14 to 28 days post-immunization (dpi). The differential leukocyte count of neutrophils and monocytes were significantly higher than those in the control group at 14 dpi. Additionally, the number of lymphocytes increased significantly and reached a peak at 28 dpi. The serum antibody levels were significantly increased at Day 14 and continued until 42 days post-vaccination. The mRNA expression levels of immune-related genes (IFN-1, TLR22, IL-1?, MHC I, Mx and IgM) were significantly upregulated in liver, spleen, kidney and hindgut after immunization. Four weeks post-immunization, fish were challenged with virulent GCRV by intraperitoneal injection. The results of this challenge study show that orally immunized group exhibited a survival rate of 60% and relative percent survival (RPS) of 56%, whereas the control group had a survival rate of 13% and RPS of 4%. Taken together, our results demonstrate that the silkworm pupae powder containing baculovirus-expressed VP35-VP4 proteins could induce both non-specific and specific immune responses and protect grass carp against GCRV infection, suggesting it could be used as an oral vaccine.

Project description:BackgroundN-ethyl-N-nitrosourea (ENU) mutagenesis is a useful method for the genetic engineering of plants, and the production of functional mutants in animal models including mice and zebrafish. Grass carp reovirus (GCRV) is a haemorrhagic disease of grass carp which has caused noteworthy losses in fingerlings over the last few years. To overcome this problem, we used ENU mutant grass carp in an attempt to identify functional resistance genes for future hereditary rearing projects in grass carp.ResultsThis study used ENU-mutated grass carp to identify genetic markers associated with resistance to the haemorrhagic disease caused by GCRV. Bulked segregant analysis (BSA) was performed on two homozygous gynogenetic ENU grass carp groups who were susceptible or resistant to GCRV. This analysis identified 466,162 SNPs and 197,644 InDels within the genomes of these mixed pools with a total of 170 genes annotated in the associated region, including 49 genes with non-synonymous mutations at SNP sites and 25 genes with frame shift mutations at InDel sites. Of these 170 mutated genes, 5 randomly selected immune-related genes were shown to be more strongly expressed in the resistant group as compared to the susceptible animals. In addition, we found that one immune-related gene, EPHB2, presented with two heterozygous SNP mutations which altered the animal's responded to GCRV disease. These SNPs were found in the intron region of EPHB2 at positions 5859 (5859G > A) and 5968 (5968G > A) and were significantly (p = 0.002, 0.003) associated with resistance to GCRV. These SNP sites were also shown to correlate with the GCRV-resistant phenotype in these ENU grass carp. We also evaluated the mortality of the different ENU fish genotypes in response to GCRV and the SNPs in EPHB2. The outcomes of these evaluations will be useful in future selections of GCRV-resistant genes for genetic breeding in grass carp.ConclusionOur results provide a proof of concept for the application of BSA-sequence analysis in detecting genes responsible for specific functional genotypes and may help to develop better methods for marker-assisted selection, especially for disease resistance in response to GCRV.

Project description:Grass carp is an important farmed fish in China that is affected by serious disease, especially hemorrhagic disease caused by grass carp reovirus (GCRV). The mechanism underlying the hemorrhagic symptoms in infected fish remains to be elucidated. Although GCRV can be divided into three distinct subtypes, differences in the pathogenesis and host immune responses to the different subtypes are still unclear. The aim of this study was to provide a comprehensive insight into the grass carp response to different GCRV subtypes and to elucidate the mechanism underlying the hemorrhagic symptoms.Following infection of grass carp, GCRV-I was associated with a long latent period and low mortality (42.5%), while GCRV-II was associated with a short latent period and high mortality (81.4%). The relative copy number of GCRV-I remained consistent or decreased slightly throughout the first 7 days post-infection, whereas a marked increase in GCRV-II high copy number was detected at 5 days post-infection. Transcriptome sequencing revealed 211 differentially expressed genes (DEGs) in Group I (66 up-regulated, 145 down-regulated) and 670 (386 up-regulated, 284 down-regulated) in Group II. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed significant enrichment in the terms or pathways involved in immune responses and correlating with blood or platelets. Most of the DEGs in Group I were also present in Group II, although the expression profiles differed, with most DEGs showing mild changes in Group I, while marked changes were observed in Group II, especially the interferon-related genes. Many of the genes involved in the complement pathway and coagulation cascades were significantly up-regulated at 7 days post-infection in Group II, suggesting activation of these pathways.GCRV-I is associated with low virulence and a long latent period prior to the induction of a mild host immune response, whereas GCRV-II is associated with high virulence, a short latent period and stimulates a strong and extensive host immune response. The complement and coagulation pathways are significantly activated at 7 days post-infection, leading to the endothelial cell and blood cell damage that result in hemorrhagic symptoms.

Dataset Information

Genetic variations of body weight and GCRV resistance in a random mating population of grass carp.

Publications

Genetic variations of body weight and GCRV resistance in a random mating population of grass carp.

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